Using pthread and message queue with QProcess : problem

Dcqt

this is just the outline of my problem .

please can somebody provide some solution.
@
int main()
{
Mainwindow w;
}

Mainwindow :: Mainwindow()
{
call_actions();

}

call_actions()
{
QProcess *newproc1 = QProcess;

pthread_create(tid,NULL,wait_for_message_from_appl,NULL);
}
int msgid;
int key = 0x1234;

void * wait_for_message_from_appl ( void *)
{

msgget(msgid);
msgrcv(msgid,msg);
if (msg == appl1)
launch(app1);
}

launch(app1)
{
QProcess *newproc2 = QProcess;

     msgrcv(msgid); // this is failing saying Interrupted system call

wait_for_exit();// this will come from newproc2 , i will send msg

}@

interface_file.c (newproc1 process)
@
msgid = msgget(0x1234);
msgsnd(app1); -- will go to wait_for_message_from_appl@

applicaion_file.c (newproc2process)
@ if(exit)
msgid = msgget(0x1234);
msgsnd(msgid,"exit");//----- this shoud go to newproc2@

the second time i use msgrcv ( in newproc2) i am getting msg saying "Interrupted system call".

what is problem.

please suggest me some other way by which i can achieve the same (my design skills are really poor)